Electric furnace.



PATENTED APR. l17. 1906.

J. F. HAMMUND.

ELECTRIC FURNACEx APPLIOATION FILED APR.13. 1905'.

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UNITED STATES PATENT OFFICE.

ELECTRIC FURNACE.'

Specification of Letters Patent.

Patented April 17, 1906.

AApplication filed April13. 1905. Serial No. 255,263.

To al?. 10h/0m, it 71am/ concern.-

Be it known that I, JOHN F. HAMMOND, a citizen of the United States, residing in Brewster, in the county of Putnam and State of New York, have invented certain new and useful Improvements in Electric Furnaces, of which the following is a specification.

This invention relates to the class of electric furnaces which receive their heat by passing a Current of electricityr through suitable conductorsA located in proximity to or embedded in a suitable inuflle.

It is an object of the inventionto provide a simple, economic, and/efficient arrangement whereby the furnace may be heated and also means whereby the amount of heat may be regulated and its adm ission to the muflie readily controlled.

Itis also'comprehended in the invention to provide means whereby objectionable sparking will be practically eliminated when the current-changing device moves from one contact to another' to cont-rol the course of the current.

In the accompanying drawings, forming a part of this specification, is shown one of the embodiments of my invention, whereon Figure 1 is a front elevation, partly broken away. Fig. 2 shows a side elevation, also partly in section. Fig. 3 is a fragmentaryvv top or plan view. Fig. 4 is a perspective view of the inutile, vpartly broken away. Fig. 5 is a perspective view-of a portion ofthe current changing device. Fig. 6 shows diagrammatically the current-changing device in connection with the system of wiring used in the present case, and Fig. 7 shows a detail of the terminals that are connected by the roller-switch.

The furnace may be of anyl suitabletype according to its intended application and in the present instance is shown as a ceramic furnace specially adapt-ed for use in connection with the manufacture of jewelry and dental articles.

-In the accompanying drawings the reference-numeral 7 indicates. the muffle (shown separately in Fig. 4)-that is, shown as having two separated windings 8 and Q-prcferablyof platinum wire, arranged on the surface of its inner wall or embedded aslight distance therein.l Upon the current being passed through these coils the mutiie will be heated to a degree dependent upon the amount of current flowing therethrough. The inutile may have an outer casing 10, and between it and the muflie proper a suitable refractory i material is placed, such as fire-brick or firei clay. The casing 10 is inclosed in a suitable i frame 30, mounted on a pedestal 33, whereby i the whole is supported. The casing 10 is offset from the mufiie, except at the ends, by means of annular ring portions 36, thereby providing a space around the convex portion of the casing 10. The top of the outer casing 3() may have suitable apertures 37 for ventilation ofsuch space. v

At the top of the casing 10 are larranged two series or rows of separate blocks or projections 11 of insulating material. A resistance-coil 12, made of suitable material, such as nickel wire, is wound around the outside of the casing 10 fromend to end, and as each Winding passes over the top it is placed between the alternate projections 11 of each series. A similar coil 13 is wound on the casing 10, each winding being intermediate of the windings of said coil, and at the top passing between the alternate projections 11 of each row. Where these two coils pass from one set of projections to the other, they are bent substantially V- shaped, as shown in Figs. 3 and 7 but each is separated from the other and rests on the top of the casing 10,5 that is made of insulating material.

The extremities of the heating-coils 8 and 9, embedded in the mufiie, at one end connect with a terminal 14 by a lead 15. The other end of the heating-coil 8 connects withV one end of the resistance-coil 13, while the other end of the inner coil 9 connects with one end of the resistance-coil 12. The said other end of the coil 8 also connects by a wire 16 with a terminal plate 25. The device for controlling the portions of such resistance-coils 12 and 13, that are included in series with the f heating-coils 8 and 9, comprises a roller-contact 20, supported on an arm 23, secured to a head 21. The latter is slidable on two parallel rods 19, secured at their ends by brackets 17 and 26 to the top of the furnace. A handle 22 serves to advance the head, and thereby cause the wheel 20 to pass between the two sets of projections 11 and have a rolling engagement with the V-shaped portions of the two resistance coils 12 and 13. The other lead 18 from the source of current is connected with the extremity of one of the rods 19, thereby placing the wheel20 in circuit between said terminal and the V-bends.

At the initial position when the current is 'first caused' to .flow through the leads the IOL wheel 20 will be located on the contact-plate winding less in circuit than in the latter posi- 25, but will not connect with any of th retion, which convolution connected the porsistance-wires, as indicated diagrammatiction 121 with the portion 12'2. In other ally in Fig. 7. The broken lines a, b, c, d, e, words, the resistance is reduced for the ciirand j' indicate the line of contact with the rent passing through the coil 8. 1vThe next 7o wheel, and the lines 121 122 123 anu 131 132 succeeding position e will bring the wheel to 133 indicate, respectively, the portions of leave the wire 131 and now connect the wires the coils 12 and 13 engaged by the Wheel. 122 and 132. This will produce a parallel In this initial position the current/will pass circuit of two branches, one branch including 1o first into the rod 19 and wheel 20, thence by the coil 8 in series with the reduced ortion of 7 5 late 25'through wire 16 to one end of the the coil 13 and the other branch inc uding the eating-coil 8. After traversing this coil the other heating-coil 9 now in series with the recurrent will be led out by the lead 15. This sistance-coil 12, reduced by one convolution, will cause the Whole'of the current to pass and each succeeding stage or position of the 15 through one only of -the two heating-coils, Wheel by which one of the wires is cut out and 8o which will have the effect of slightly warma new one cut in will reduce one of the resisting the muf'de. Upon advancing the Wheel ances 12 or 13 by one convolution, untiliat 2O to the position b lfrom Fig. 7 it will be obthe final position the resistance has been enserved that one extremity of the resistancestirely cut out and the coils 8 and 9 are'in parzo coil 12 will now be in circuit witli the positive allel circuit directly connected between the 85 lead and that a branch of the circuit will be leads, thereby admitting the greatest amount established throughout the length of this coil, of current to them and producing the maxithe current thence traversing the other heatmum heating effect; but it will be observed in -coil 9 and passing out by lead 15. This that in each instance the wheel contacts with 2 5 Wil give a parallel circuit through the two the apex of the V-shaped terminals, as they 9o .heating-coils; but one of them Wi l have the might be considered7 before it leaves the exentire ength of the resistance-coil 12 in cirtre'mities of such V-sha ved portion of the cuit with it. This will at once reduce the same wire, therebyin eac instance making a current owingthrough the coil 8 and tpreshunt around the convolution before cutting 3o vent overtaxing this coil before it has sufit out of circuit. 95 ciently increasedits temperature to offer an Having thus described my invention, I increased resistance to the current. ,On the claimnext advance of the wheel to the position cit A1. In a furnace, the combination with a will be observed from Fig. 7 that by reason muflfle whose interior is wound with a heat- 35- of the V shape of the terminals or portions of generating wire, of a casing for said muflie roo the circuit engaged by the wheel that the and whose exterior is Wound with a resistwheel is still incontact, but about leaving ancewire,both of said wires being connected,

the plate 25, lthat it isalso still in contact and means for traveling from one to another with the portion of the coil 12, but that it has of the convolutions ofithe resistance-coil for 4o no w just made 1contact with the extremity of varying the resistance. 1o 5 the other resistance-coil 13. This will es- 2. In a furnace, the combination with a tablish anotherV branch in parallel with the mufiie'whose interior is Wound with platinum parallel circuits of the latter position b, the wire, of a casing for said muilie, and whose third branch being through the entire length exterior is wound with nickel wire, `both of 45 of the resistance-coil 13 and thence through said wires vbeing connected, the convolutions I Io the coil 8; but the latter bein connected by of said nickel wire being so bent, at portions thev Wire 16 with the coil 13 t ewire 16 will parallel to each other, that the bend of one form a; shunt around the coil 13, practically wire will lie within the bend of another wire, cutting it out of operation until a slight -adand a device for traveling along said bends 5o vance from this position will cause the Wheel for varying theresistance. I I5 to leave the plate 25 andbe inengagement with- 3. In a furnace, the combination With a the wires 121 and 131. The circuit will now be mufiie internally Wound with a heat-generat- A-in a parallel of two branches, one branch being ing Wire, of a casing therefor, and which is exthrough the resistance 12 and thence through ternally wound, with a resistance-wire, each 5 5 the coil 9 and the other branch, including convolution of the resistance-wire being bent 1 zo the resistance 13, in series with the coil 8. so as to lie'in the bends of the other' convolu- The next succeeding positiond will brin the tions, a meniber for riding over said bends, wheel to connect the two portions 131 any 122 means to sup ortyand actuate said member, of the coils 12 and 13. This will establish a and means or: Asupporting said actuating 6o parallel circuit of tw'o branches, one branchl means. l g

including the entire resistance-coil l3in seriesf1 .4. In a furnace, the combination with la v'ith its corresponding heatingtcoil 8, while", ".mufiie internally wound with a heat-generatthe other .branch will include the other heating. Wire, of a casing therefor, and which is exing-coil 9 in series with a portion of thereternally woundwith a resistance-wire, each 6 5 sistance-coil 12, having one convolution Yor. convolution of the resistance-Wire being bent `1 3e so as to lie in the bends ofthe other convolutions, a rotatably-n'iounted member for riding over said bends, and which will contact with one bend before it breaks contact with another, means to support and actuate said member, and means for supporting said actuating means, one of the wires being connected with said supporting means.

5. In a furnace, the combination with a casing provided with grooves, of rows of separators registering with said grooves, a resistance-wire convoluted in said grooves and passing between said separators; that portion of each convolution which lies between the rows of separators being so bent that one bend will lie within the bend of another, a muH'le internally wound with a heat-generating wire, and which is connected with said resistance-wire, a shoe for traveling along t-he bends of said resistance-wire, and means for guiding said shoe. i

6. In a furnace, the combination with a muffle of a heat-generatingeoil on'the interior of said muflle, a resistance-coil on the exterior of said mutfle, and which is connected With the heat-generating coil, and means for varying the amount of resistance.

7. In a furnace, the combination with a muiiie whose interior is wound with platinum wire, of a casing for said muffle whose exterior is wound with nickel wire, both of said wires being connected, the convolutions of said nickel wire being so bent at portions parallel to each other' that the bend of one wire will lie Within the bend of another, and a device for traveling along said bends for varying the resistance. Y

8. In a furnace, the combination with a mufile Whose interior is wound with platinum wire, of'a casing for said mufile, and whose exterior is wound with nickel wire, both of said wires being connected, the convolutions of said nickel wire being so bent at portions parallel to each other that the bend of one wire will lie within the bend of another wire, and a' rotating device for travelingalong said bends for varying the resistance, and said resistance device being adapted to contact with one convolution before it leaves Vthe other. A

9. In a furnace, the combination with a muflle internally wound with a heat-generating wire, of a casing therefor, and which isexternally Wound with a resistance-wire, each convolution lof the resistance-wire being bent so as to lie in the bends of the other convolutions, a rotating member for riding over said bends, a sliding head to support said rotating member, and rods for supporting saidhead.`

10. In a furnace, the combination with a muli'le internall) wound with a heat-generat ing wire, of a/casing therefor having grooves therein which is wound'with a resistancewire, each convolution of the resistance-wire being bent so as to lie in the bends ofthe t other convolutions, a wheel for riding over said bends, means to support-and actuate said wheel, and 'guides for supporting said actuating means, one of the wires being coni nectedto said guides.

11. In a furnace, the combination with a casing rovided with external grooves of two paralle rows of separators registering with said grooves, a resistance-wire convoluted in said grooves and passing between said separators, and which are bent to suitable form between said rows a inutile internallyY wound with heat-generat-ing wire, andv which iscon nected with said resistance, a rotary shoe for traveling along the bends of said resistancewire., and means for guiding said shoe.

12. In a furnace, the combination with a ceramic Inutile, of a platinum coil on the interior of said inutile, a casing, a resistancecoil on the exterior of said easing, and means for varying the amount of resistance.

13. In a'furnace, the combination with a inutile whose interior is wound with platinum wire, of a casing for said inutile, and whose exterior is wound with nickel wire, both of said wires being connected, the eonvolutions of said nickel wire being so bent at portions parallel to each other that the bends will be V-shaped and will lie within each other, and a device for traveling along said bends for varying the resistance. i'

14. In a furnace, the vcombination with a muflle whose'interior is wound with platimnn wire, of acasing for said muffler, and whose exwires being connected, the. convolutions of said nickel wire being so bent at ortions parallel to each other that the bend) of one wire will lie within the -bend of another wire, a device for traveling along said bends for parting the resistance, and Asaid resistance'device bein(lr adapted to Contact with one convolutionlbefores it leaves the other, and an outer finishing-casing.

15. In a furnace, the combination with a muflie internally wound with a heat-Generatl'ng wire, of a casing therefor, which is externally wound with a resistance-wire, each convolution ot the resistance-wire being bent tions, a rotating member for riding over said bends, a shdine' head for carrying said member, a handle for operating said head mem- 'ber, and means for su )porting said head.

16. In ya furnace, t 1e combination with a-y mufle internally wound with a heat-generating wire, of a casing therefor, and which is ex` convolution of thel resistance-wire being bent so as to lie in the bends ofthe other eonlvolutions, a rotatably-,mounted member 4for riding over said bends, a sliding headfor sup- -wires being connected to said support.

terior is wound with nickel wire, both of said i.

so as to lie in the bends of the other convolu iro ternally wound with a resistance-wire, each porting said member, means for actuating said head, a support for said bead, one of the with the first resistance-coil; upon a further advance of the connector a shunt will be eswith the second resistance-coilgat afurther advance of the connector the same parallel nector, said terminals being arranged to cop- .the convolutions of the resistance-coils will Aand the translating-coils will belconnected in ,parallel across the leads.

1 7. In a furnace, the combination with a l casing provided with rooves, of rows of separators registering wit said grooves, a resistance-wire convoluted in said grooves and passing between said se arators, and which are bent to suitable formlbetween said rows, a muffle internally wound with heat-generating wire and which is connected with said resistance-wire and a rotary shoe for traveling along the bends of said resistance-wire and means for guiding' said shoe.

18. In an electric translating device, the combination `of a translating-coil, a second translating-coil, a resistance-coil, a second resistance-coil,l a connector member, a pair of feed-wires, and terminals 'connected with said wiresl and arranged to be engaged by such connector, said terminals being arranged to cooperate with -the connector, whereby the connector will first connect the first translatin coil with the feed-wires, thereu on the advance of the connector, a parallel circuit of two branches will be established across the leads, in which one branch includes said first translatin -coil and the other branch includes the secon translating-coil arranged in series tablished in the branch including the first translating-coil, which shunt includes the scvond resistance-coil; upon a still further advance of the connector the second resistance-'- coil will be established in series with the first translating-coil on one branch ofthe aforesaid parallel circuit and at afurther advanced position of the connector the two said resistance-coils will be cut out, leaving. the two translating-coils in parallel across the leads.

19. In an electric translating device, the combination of a translating-coil, a second translating-coil, a resistance-coil, a second resistance-coil, a connector member, a -pair of feed-wires, and terminals connected with said wires and arranged to be engaged by such con-v erate with the connector, whereby the connector will establish a parallel circuit of two branches, in which one branch includes the first translating-coil connected in series with. the first resistance-coil, and the other branch includes the second translating-coil in series series arrangement Will be effected, but with one convolution of each said resistance-coils being cut out, thereby reducing the amount of resistance in circuit with each translatingcoil; upon further advance of the connector be successively cut out, until at the final position the resistances will be entirely cut out 20. vI n an electric translating device, the

combination of a translating-coil, a secondi translating-coil, a resistance-coil, a second resistance-coil, a connector member, a air of feed-wires, and terminals connecte with said wires and arranged to be engaged by such connector, said terminals being arranged to coperate with the connector, whereby the connector will establish a parallel circuit of two branches in which one branch includes the first translating-coil in series with the first resistance-coil, and the other branch includes the second translatin -coil in series with the second resistance-coiI; at a further advanced position of the connector the first resistance-coil will have 'a shunt established around one of its convolutions, and upon a further advance the said convolution will be cut out4 of circuit; at a still further advance the second resistance-coil will have a shunt established around one of its convolutions, and upon a still further advance the said latter convolution will be cut out; and the succeeding position of the connector will cause alternately a reduction of the number of convolutions in the two resistance-coils,until at the final position the two translatin -coils will be connected in parallel across the eads.

21. In an electric translating device, the combination of a translating-coil, a second translating-coil, a resistance-coiL. a second resistance-coil, a pair of leads, one of such leads being connected with the front end of each of the translating-coils, the other lead being connected with a movable switch member and arranged to remainl in connection therewith throughout its range of movement, a contact-plate connected with the other extremity of said first translating-coil and also connected with the' rear end of said second resistance-coil, the rear end of said first resistance-coil being connected with'the rear end of the first translating-coil, said switch member being movably supported to first engage with said contact-plate and thereupon engage alternately with the convolutions of the two resistance-coils successively from their front end to their said rear end.

22. In an electric translating device, the combination of a translating-coil, a second translating-coil, a resistance-coil, a second resistance-coil, a pair of leads, one of such leads being connected with the translatin -coils,the other leadbeing connected wit a movable switch member and arranged to remain in connection therewith throughout its range of movement, a contact-plateconnect'ed with the other eX- the front end of each of tremty of saidfirst translating-coil and also connected with the rear end of said second resistance-coil, the rear end of said first resistance-coil being connected with the rear end of the first translating-coil, said switch member being movably supported to rst engage with said contact-plate and thereupon" engage alternately with the convolutions .of themtwo resistance-coils successively from theirlfront end to their said rear end, the enL translating-coil, a resistance-coil, a second resistance-coil, a pair of leads, one of such leads being connected with the front end of each of the translating-coils, the other lead being connected'with a movable switch member and arranged to remain in connection therewith throughout its range of movement, a contact-plate connected with the other eX- tremity of said first translating-coil and also connected withthe rear end of said second resistance4coil, the rear end of said first reeimer sistance-coil being connected with the rear end of the iirst translating-coil, said switch member being movably supported to lirst engage with said contact-plate and thereupon engage alternately with the convolutions of the two resistance-coils successively from their front end to their said rear" end, said engagingportions of the convolutions cornprising a series of V-shaped portions overapping but insulated from each other, whereby the switch member will constantly engage two of such convolutions not in the same coil.

Signed at Nos. 9 to 15 Murray street, 'New York, N. Y., this 11th day of April, 1905.

JOHN RHAivn/ioNn; 

